Novel reforming catalysts

ABSTRACT

Crystalline aluminosilicate zeolites are mixed with conventional reforming catalysts to produce new catalytic compositions with high catalytic activity and selectivity and excellent aging characteristics. These new catalytic compositions may be utilized alone or in conjunction with conventional reforming catalysts. The acidic activity of the total catalyst system is controlled within defined limits. When so controlled the utility of these catalyst systems in reforming hydrocarbon mixtures is to reduce the C 1  and C 2  concentrations in reformer gas product, while increasing the C 3  and C 4  concentrations and maintaining high liquid yield at high octane numbers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.503,131, filed Sept. 4, 1974, which in turn in a continuation-in-part ofU.S. application Ser. No. 262,410, filed June 13, 1972 and both nowabandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to novel catalytic compositions and their use asreforming catalysts. More specificially, these catalysts comprise thejoint use of zeolites with conventional reforming catalysts such asplatinum or platinum-rhenium or multi-metallics on alumina.

2. Description of the Prior Art

Catalytic reforming of naphtha feed stocks has long been known in thepetroleum industry. Most naphtha feeds contain large amounts ofnaphthenes and paraffins and consequently have low octane members. Bymeans of various hydrocarbon conversion reactions, catalytic reforminghas improved the octane number of naphtha feed stocks. Some of the moreimportant conversion reactions that take place during catalyticreforming are dehydrogenation of naphthenes to aromatics,dehydrocyclization of paraffins to napthenes and aromatics andisomerication of normal paraffins to isoparaffins. A less desirablereaction that also occurs during reforming is the hydrocracking of longchain paraffins to gaseous hydrocarbons such as methane and ethane.

The above reforming reactions have previously been catalyzed tocatalysts comprising porous supports, such as alumina, that havedehydrogenation promoting metal components impregnated or admixed withthe support. Platinum on alumina and, more recently, multimetallics,including bimetallics, such as platinum and rhenium on alumina, areexamples of these catalysts.

Reforming catalysts should possess high selectivity, high activity andgood stability. Selectivity in reforming is the ability of a catalyst toselectively produce high yield of high octane products, such asaromatics, from compounds that have relatively low octane numbers, suchas naphthenes and paraffins. The activity of a catalyst is the abilityto convert the feed stock into all products without regard toselectivity. A stable catalyst is highly desirable so that the activityand selectivity characteristics of a catalyst can be maintained duringprolonged periods of operation.

It is known in the art to admix certain zeolites with other catalyticmaterials. For instance, Brithish Pat No. 1,056,493 discloses mixingtogether an alumina-supported platinum catalyst and a chabazite zeoliteand using it in a hydrocracking operation. British Pat. No. 1,255,544discloses a dual purpose catalyst comprising a zeolite, especiallymordenite, having incorporated therein both platinum and rhenium.However, these patents do not suggest the catalysts of this inventionsince they do not afford the same advantages. The octane numberimprovement and their remarkable ability to withstand aging with thecatalysts of this invention are significantly greater than can beobtained with the catalysts of the British patents mentioned.

U.S. Pat. No. 3,267,022 and U.S. Pat. No. 3,324,047 disclose compositesof a zeolite having a pore size of from 6-14A and an adjuvant such asalumina. Hydrogenation activity is said to be imparted by adding, forexample, a Group VIII metal, either to the zeolite or to the adjuvant.The amount of zeolite is from 20-80% by weight.

U.S. Pat. No. 3,544,451 refers to a hydrocarbon conversion catalystwhich comprises platinum and rhenium combined with a carrier materialcontaining alumina and finely divided mordenite. As will be shownhereinafter, combinations similar to those of the patent are ineffectivefor the purposes of the present invention.

U.S. Pat. No. 3,702,886 discloses a composite of from 1- 90% of azeolite, such as ZSM-5, with a matrix material and a hydrogenationcomponent. The matrix materials include generally metal oxides, but notspecifically alumina.

As another example of the state of the art, U.S. Pat. No. 3,758,402discloses the hydrocracking of hydrocarbons to motor fuel products bycontacting a hydrocarbon charge with a catalytic mixture containinghydrogenation components, a large pore size zeolite such as zeolite X orY and a smaller pore size zeolite such as ZSM-5 and a matrix material,an example of which is alumina. The zeolite components may comprise from1-95% of the final composite.

U.S. Pat. No. 3,365,392 discloses the catalytic reforming of gasolinecharge stock to produce high octane reformate and LPG by contacting acharge with a catalyst comprising a platinum group metal on a supportcomprising a finely divided crystalline aluminosilicate suspended in analumina matrix. The preferred aluminosilicate is the hydrogen orpolyvalent form of mordenite, especially the hydrogen form thereof.

U.S. Pat. No. 3,546,102 is concerned with a hydrocarbon conversioncatalyst consisting essentially of a co-catalytic support and a GroupVIII metal. The support contains an adsorbent refractory inorganic oxideand mordenite structure zeolite. The preferred metal is platinum, and itis incorporated into the xeolite-inorganic oxide blend after blendingbut before drying and calcining.

Other U.S. patents disclosing catalytic composites comprising platinum,or rhenium, or both, optionally a matrix and mordenite as the sole orpreferred crystalline aluminosilicate are U.S. Pat Nos. 3,369,997,3,376,214, 3,376,215, 3,464,929, 3,511,773, 3,523,914, 3,562,108 and3,574,092.

All of the U.S. patents mentioned, can be distinguished on one or bothof two different grounds. The first, already mentioned in connectionwith U.S. Pat. No. 3,544,451, is that it is conclusively shown hereinthat mordenite composites are inferior. The second is that no patentmentioned teaches or even suggests the extraordinary stability at highliquid yields at high octane numbers of the composites of this inventionby controlling the activity so that its activity function will fallwithin the limits to be hereinafter defined.

SUMMARY OF THE INVENTION

Zeolites of controlled activity are mixed with reforming catalystsyielding a catalyst composite (sometimes called "composite A" or simply"catalyst A" hereinbelow) with improved selectivity and agingcharacteristics.

The catalysts of this invention have the ability, when compared tocommercially available reforming catalysts, to reduce the C₁ and C₂concentrations in the effluent gas while increasing the C₃ and C₄yields. This necessarily improves the selectivity of the catalyst andincreases the yield of high octane products. The catalyst is also moreactive and much more resistant to aging than conventional reformingcatalyst and give higher octane number products at given conditions.

In essence, the invention concerns the reforming of hydrocarbons bycontacting same under reforming conditions with a catalyst system inwhich the total catalyst comprises from about 1% to about 100% of acomposite comprising (a) an effective amount, up to about 25%, by weightof a crystalline aluminosilicate zeolite of controlled acidity, (b) notless than about 75%, by weight, of a carrier material, (c) from about0.01% to about 2%, by weight, of a platinum group metal either alone orin combination with other metals, and (d) from about 0.01 to about 3%,by weight, of a halide and (2) from 0% to 99% of a conventionalreforming catalyst composition comprising (a) a carrier material, (b)from about 0.01% to about 2%, by weight, of a platinum group metaleither alone or in combination with other metals, and (c) from about0.01% to about 3%, by weight, of a halide, said total catalyst systemhaving a K factor from about 1.5 to about 15, this factor being asdefined in the specification in equations 2 and 3. (2) above will behereinafter sometimes referred to as "catalyst B".

DESCRIPTION OF THE INVENTION

Typical conventional reforming catalysts that may be employed in thecatalyst system of these inventions include the platinum group metalreforming catalyst, including the bi-metallic and multi-metalliccatalysts. The descriptions of such conventional catalysts, to follow,also apply to the carrier materials, preferably alumina, which comprisesthe major proportion of the zeolite-containing composite. While thesetwo materials, the conventional catalyst and the carrier material in thezeolite-containing composite, may be identical this is by no means arequirement of this invention.

The phrase "platinum group metal" includes, for example, platinum,palladium, osmium, iridium, ruthenium, or rhodium and mixtures thereofwith each other or with other metals, such as metals of Group VII-B,including rhenium, deposited on a suitable support. Generally, the majorportion of the conventional reforming catalyst will be alumina, whichmay comprise as much as about 99% by weight or more of these composites.Other components may be combined with the alumina carrier, such asoxides of silicon, magnesium, zirconium, thorium, vanadium, titanium,boron or mixtures thereof. The platinum-alumina combination, either withor without one or more of the above listed components such as silica,may also be promoted with small amounts of halogen such as chlorine andfluorine in amounts ranging from about 0.1% up to about 5% by weight.Generally, less than about 3% of halogen is employed with the standardplatinum group composite. In a perferred embodiment, the carriermaterial is a relatively high surface area material, preferably aneta-alumina or gamma-alumina material or mixtures thereof having asurface area of at least about 100 square meters per gram. Preparationof the "platinum group" component may be accomplished by differentprocedures described in the prior art. In one procedure an aluminacarrier material is impregnated with the acid or salt of one or more ofthe herein described "platinum type" hydrogenating components in amountsthat will produce about 0.01% up to about 2% by weight of the metal, butgenerally not substantially more than about 0.6% by weight of platinumis employed.

It is to be understood that a naturally occurring or a syntheticallyprepared alumina with or without silica may be employed as a carriermaterial or support. Preferably, supports are high surface area materialsuch as a base alumina as discussed above. Before use, the high surfacearea platinum-containing composites may be reduced in a hydrogenatmosphere and maintained preferably in a substantially moisture-freeatmosphere before being put on stream.

It is to be understood that the term "platinum group metal" reformingcatalyst designates materials which perform the well-known reformingreactions of hydroisomerization and aromatization under conditionscreating a low (essentially equilibrium) concentration of olefins in theeffluent product.

In preparation of the zeolite-containing component A, not less thanabout 75% of the above conventional "platinum group metal" catalyst ismixed with an effective amount, up to about 25%, preferably up to about15% by wt. of zeolite. The more preferred concentration of zeolite isabout 0.1 to about 5% or about 10% intimately mixed with theconventional platinum metal-alumina component under conditions such thatthe average particle size of the zeolite is not more than about 10microns. These percentages are based on the combined weight ofconventional reforming catalyst plus zeolite in the composite A. Theexact amount of zeolite that is mixed with the platinum-metal on aluminacomponent depends upon the K factor described hereinbelow and thepretreatment conditions both of which are directly concerned with theactivity of the zeolite catalyst.

The activity and aging characteristics of reformer systems areremarkably controlled by catalyst composites of this invention which areprepared with regulated degrees of acidity. Because catalyst compositesof this invention have higher acidities than conventional reformingcatalysts, the acidity of the total reformer system that containszeolite composites in either all or part of the total reformer, will besomewhat greater than for conventional systems. Thus we found that theacidity of the total reformer catalyst system (A plus B) when properlycontrolled gave a blanched activity and aging characteristics. Thisoccurred when the K factor was not less than about 1.5 and not greaterthan about 15. The K factor for a total reformer system is defined as afunction of the rate at which all catalysts in a system isomerizeso-xylene to m- and p-xylenes compared to that at which a standardreforming catalyst (minus any zeolite) isomerizes o-xylene under thesame condition. Further the "Relative Activity" for a given composite isdefined as the rate at which the composite isomerizes o-xylene to m- andp-xylenes compared to that at which the standard reforming catalystminus any zeolite isomerizes o-xylene under the same conditions.

Isomerization activities of these composites were measured in anisothermal downflow tubular glass reactor at atomspheric pressure. Thereactor bed of approximately 0.5 grams of 14 ×25 mesh pre-reducedparticles was preceded by a preheat section containing 3 cc of 8/10 meshquartz chips. The preheat and catalyst bed sections were both maintainedat the same temperature. The catalyst was heated to 1000° F at a rate of10° F per minute in a 100 cc per minute hydrogen flow. After 1 hourhydrogen addition was discontinued and the catalyst cooled to 900° Fwith a helium purge. At 900° F the purge was stopped and ortho xyleneadded at a rate of 2.5 ± 0.5 grams per gram of catalyst per hour. Liquidreactor effluent was collected and anaylzed by gas chromatography. Theconversion of ortho xylene to meta plus para xylenes was calculated perone-half gram of catalyst. The % conversion of the o-xylene per one-halfgram of the standard catalyst under these reaction conditions is 1.1%.The catalytic rate constants for conversion of ortho xylene to metaxylene and para xylene relative to that for an equal weight of thestandard commercial platinum-rhenium catalyst were determined by thefollowing equation for the liquid effluent collected between 50 and 70minutes on stream. ##EQU1## where X_(e) = concentration of o-xylene atequilibrium,

X = ortho xylene concentration in the liquid product from one-half gramof the experimental catalyst and

Y = the ortho xylene concentration given at the same conditions byone-half gram of the standard catalyst (R16H). All concentrations are inmole fractions.

This is a first order rate equation for a reaction which can proceed toequilibrium.

At the standard temperature of 900° F the value of X_(e) = 0.25 and withthe specified standard the value of Y was found to be 0.989 so theequation reduces to ##EQU2##

Thus for the purposes of this disclosure the term "standard reformingcatalyst" shall mean a specific commercially available reformingcatalyst containing 0.37% Pt and 0.20% Re and 0.9% chloride impregnatedon gamma alumina (see Example 7) which gives an o-xylene conversion of1.1% per 0.5 grams at the above specified test conditions.

Later discussion indicates that the mixed zeolite "platinum group metal"on alumina composition may be used in all reactors or only a portion ofthe reactors depending on the specific product properties and agingcharacteristics sought. With the zeolite-containing composite in lessthan all the reactors a conventional non-zeolite catalyst is used in theremainder.

Thus it is necessary to define an activity function for the totalcatalyst used in the total reformer system. That is, we need to define arelative acid activity for the total catalyst in the system. We havecalled the function simply K. K for the catalyst system is calculatedvery simply from the relative activities of the zeolite-containingcomposite A and of the non-zeolite conventional reforming catalyst B, ifpresent.

K = (Relative Acid Activity of Zeolite Composite) × (Vol. % of ZeoliteComposite) + (Relative Acid Activity of Non-Zeolite Composite) × (Vol %of Non-Zeolite Composite). In practice, K can, as already stated, rangefrom about 1.5 to about 15. Preferably, it will range from about 1.5 toabout 10, more preferably from about 2 to about 5.

As will be illustrated hereinafter, it has been found that when the Kfactor is from 1.5 to about 15 the mixed zeolite-reforming catalystsshow significant improvement in stability toward aging during reforming,while still maintaining high liquid yields at high octane number.Conversely, when the K factor is below about 1.5, the catalyst inreforming reactions deteriorates rapidly to a point of inactivity.

Further, K factors above 15 lead to catalysts that are too highly acidicto give optimum liquid reformate yields (C₅ +) along with the desiredresistance to aging. In such catalysts, when the K factor is high, C₃ +yields are high, but high octane liquid yields are low. As an example,some fresh zeolites, such as fresh ZSM-5 (as defined below), when mixeddirectly with conventional reforming catalyst will lead to such results.Specifically, when 2% fresh HZSM-5 was mixed with 98% of a commercialplatinum (0.35%) on eta-alumina and used throughout the whole bed, thecomposite gave very high C₃ and C₄ yields and low C₅ + yields. The Kfactor of such catalyst was 32.5. Thus, the need for close control ofthe K factor is evident.

As has already been alluded to, the K factor can be controlled bycontrolling the acidity, and thus the activity, of the zeolite. Varioustechniques can be used to control the degree of acidity of the finalcatalyst composite. One technique is to treat the zeolitic component,either before or after mixing with the platinum metal-alumina component,with air or steam at elevated temperatures e.g. up to about 1700° F inair or at from about 800° F to about 1700° F in steam. It may also becontrolled by adding alkali or alkaline earth metals or metal cations tothe zeolite, again before or after compositing with the platinum-metalalumina base. Another way is to reduce the alumina content of thezeolite so that the SiO₂ /Al₂ O₃ ratio increases and the cation contentdecreases. A final illustration is the control of the zeolite content sothat the desired degree of acidity is obtained.

Among the zeolites that are useful in the practice of the presentinvention are tetraethylammonium (TEA) mordenite, calcium faujasite Y(CaY), ZSM-5 (disclosed and claimed in U.S. Pat. No. 3,702,886), ZSM-11(disclosed and claimed in U.S. Pat. No. 3,709,979) and ZSM-35 (disclosedand claimed in copending U.S. application Ser. No. 528,061, filed Nov.29, 1974). The patents and the U.S. application referred to are herebyincorporated herein by reference. ZSM-5 has the characteristic X-raydiffraction pattern as set forth in Table 1 hereinbelow. It can also beidentified, in terms of mole ratios of oxides, as follows:

    0.9 ±0.2 M.sub.2/n O : W.sub.2 O.sub.3 : 5-300 YO.sub.2 : zH.sub.2 O

wherein M is a cation, n is the valence of said cation, W is selectedfrom the group consisting of aluminum and gallium, Y is selected fromthe group consisting of silicon and germanium, and z is from 0 to 40.

Preferably the mole ratios of oxides will be as follows:

    0.9 ± 0.2 M.sub.2/n O : W.sub.2 O.sub.3 : 5-300 YO.sub.2 : zH.sub.2 O

where M, n, W, Y and z are as just defined. In a preferred synthesizedform, the zeolite has a formula, in terms of mole ratios of oxides asfollows:

    0.9 ± 0.2 M.sub.2/n O : Al.sub.2 O.sub.3 : 5-100 SiO.sub.2 : zH.sub.2 O

and M is selected from the group consisting of a mixture of alkali metalcations, especially sodium, and alkyl-ammonium cations, the alkyl groupsof which preferably contain from 2 to 5 atoms.

In a preferred embodiment of ZSM-5, W is aluminum, Y is silicon and thesilica/alumina mole ratio is above 5 and generally at least 10 ranges upto at least 100.

ZSM-5 possesses a definite distinguishing crystalline structure whosex-ray diffraction pattern shows the following significant lines:

                  TABLE 1                                                         ______________________________________                                        Interplanar Spacing d(A)                                                                           Relative Intensity                                       ______________________________________                                        11.1 ± 0.2        S                                                        10.0 ± 0.2        S                                                        7.4 ± 0.15        W                                                        7.1 ± 0.15        W                                                        6.3 ± 0.1         W                                                        6.04 ± 0.1        W                                                        5.97 ± 0.1        W                                                        5.56 ± 0.1        W                                                        5.01 ± 0.1        W                                                        4.60 ± 0.08       W                                                        4.25 ± 0.08       W                                                        3.85 ± 0.07        VS                                                      3.71 ± 0.05       S                                                        3.64 ± 0.05       M                                                        3.04 ± 0.03       W                                                        2.99 ± 0.02       W                                                        ______________________________________                                    

These values as well as all other x-ray data were determined by standardtechniques. The radiation was the K-alpha doublet of copper, and ascintillation counter spectrometer with a strip chart pen recorded wasused. The peak heights, I, and the positions as a function of 2 timestheta, where theta is the Bragg angel, were read from the spectrometerchart. From these the relative intensities, 100 I/I_(o), where I_(o) isthe intensity of the strongest line or peak, and d (obs.), theinterplanar spacing in A, corresponding to the recorded lines, werecalculated. In Table I the relative intensities are given in terms ofthe symbols S = strong, M = medium, W = weak and VS = very strong. Itshould be understood that this x-ray diffraction pattern ischaracteristic of all the species of ZSM-5 compositions. Ion exchange ofthe sodium ion with cations reveals substantially the same pattern withsome minor shifts in interplanar spacing and variation in relativeintensity. Other minor variations can occur depending on the silica toalumina ratio of the particular sample, as well as if it has beensubjected to thermal treatment.

Zeolite ZSM-5 can be suitably prepared by preparing a solutioncomprising water, tetrapropyl ammonium hydroxide and sources of sodiumoxide, an oxide of aluminum or gallium and an oxide of silicon, having acomposition in terms of mole ratios of oxides, falling within the rangesshown in Table 2.

                  TABLE 2                                                         ______________________________________                                                                     Particularly                                                Broad   Preferred Preferred                                        ______________________________________                                        OH-/SiO.sub.2                                                                              0.07 - 1.0                                                                              0.1 - 0.8 0.2 - 0.75                                   R.sub.4 N+/(R.sub.4 N.sup.+ +Na.sup.+)                                                     0.2 - 0.95                                                                              0.3 - 0.9 0.4 - 0.9                                    H.sub.2 O/OH.sup.-                                                                         10 - 300  10 - 300  10 - 300                                     YO.sub.2 /W.sub.2 O.sub.3                                                                  5 - 100   10 - 60   10 - 40                                      ______________________________________                                    

wherein R is propyl, W is aluminum and Y is silicon. This mixture ismaintained at reaction conditions until the crystals of the zeolite areformed. Thereafter the crystals are separated from the liquid andrecovered. Typical reaction conditions consist of a temperature of fromabout 75° F to 175° C for a period of about six hours to 60 days. A morepreferred temperature range is from about 90° to 150° C, with the amountof time at a temperature in such range being from about 12 hours to 20days.

The digestion of the gel particles is carried out until crystals form.The solid product is separated from the reaction medium, as by coolingthe whole to room temperature, filtering and water washing.

The ZSM-5 is preferably formed as an aluminosilicate. The compositioncan be prepared utilizing materials which supply the elements of theappropriate oxide. Such compositions include, for an aluminosilicate,sodium aluminate, alumina, sodium silicate, silica hydrosol, silica gel,silicic acid, sodium hydroxide and tetrapropylammonium compounds. Itwill be understood that each oxide component utilized in the reactionmixture for preparing a member of the ZSM-5 family can be supplied byone or more initial reactants and they can be mixed together in anyorder. For example, sodium oxide can be supplied by an aqueous solutionof sodium hydroxide, or by an aqueous solution of sodium silicate;tetrapropylammonium cation can be supplied by the bromide salt. Thereaction mixture can be prepared either batchwise or continuously.Crystal size and crystallization time of the ZSM-5 composition will varywith the nature of the reaction mixture employed.

Zeolite ZSM-5 may also be prepared, in situ, by preparing a solutioncontaining sources of silica, alumina, alkali, water and precursors toorgano-ammonium cations. These precursors consist of compoundscharacterized by the formulas: R₁ R₂ R₃ N where R₁, R₂ and R₃ areselected from the group consisting of aryl, substituted aryl, alkyl,substituted alkyl, cycloalkyl, substituted cycloalkyl, and hydrogen andR₄ X, where R₄ is selected from the group consisting of alkyl,substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl andsubstituted aryl and X is an electronegative group. It is to be notedthat the precursor to the organo-ammonium compound can be entirely madeup of the compound characterized by the formula: R₁ R₂ R₃ N.

This in situ formation of the highly substituted cation may berepresented by the following equation:

    R.sub.1 R.sub.2 R.sub.3 N + R.sub.4 X → [R.sub.1 R.sub.2 R.sub.3 R.sub.4 N]X

where R₁, R₂ and R₃ are selected from the group consisting of alkyl,substituted alkyl, aryl, substituted aryl, cycloalkyl, substitutedcycloalkyl, and hydrogen and R₄ is selected from the group consisting ofalkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl andsubstituted aryl and X is a hydroxy or a group such as chloride,bromide, iodide, sulfate, phosphate, sulfonate, sulfite, carboxylate andcarbonate. This in situ reaction takes place in the presence of sourcesof alkali, water, SiO₂ and Al₂ O₃. This in situ reaction is highlyunexpected in the presence of such alkali.

The compound represented by the formula R₁ R₂ R₃ N may be replaced bycompounds that contain nitrogen in an aromatic ring such as pyridine,quinoline, or acridine. The nitrogen may also be contained in asaturated ring such as piperdine or 1, 2, 3, 4 tetrahydroquinoline.Additionally, R₁ R₂ R₃ N₄ may be replaced by a compound that containstwo or more nitrogen atoms such as ethylenediamine.

Table 3 lists the broad and preferred ranges for the reaction mixturenecessary to synthesize members of the ZSM-5 family (i.e. ZSM-5 andZSM-11).

                  TABLE 3                                                         ______________________________________                                                         Broad    Preferred                                           ______________________________________                                         ##STR1##       =       0.1 - 0.98                                                                               0.15 - 0.80                                 ##STR2##       =       0 - 2      0 - 1.5                                     ##STR3##       =       0.01 - 0.5                                                                               0.03 - 0.3                                  ##STR4##       =       50 - 2,000                                                                               60 - 1,000                                  ##STR5##       =       1 - 300    2 - 150                                    ______________________________________                                    

wherein M = alkali metal and at least one of the R groups is preferablyC₃ H₇.

The resulting solutions are stirred thoroughly and crystallized at atemperature above about 212° F and below 700° F in order to achievecrystallization in less than a week. The temperature is preferably about250° to 500° F. The reaction is carried out at essentially autogenouspressure of 15 to 500 p.s.i.g. for a time not less than 15 minutes.Excess pressure due to inert gases in the reaction mixture are notharmful. The reaction is carried out in a closed vessel capable ofwithstanding the pressures in this reaction. The resulting solidcrystallized aluminosilicate can be removed, filtered and washed withwater at about 60° to 200° F.

The zeolites used in the instant invention usually have the originalcations associated therewith replaced by a wide variety of other cationsaccording to techniques well known in the art. Typical replacing cationswould include hydrogen, ammonium, and metal cations including mixturesof the same. Of the replacing cations, particular preference is given tocations of hydrogen, ammonium, rare earth, magnesium, calcium, zinc,copper, silver, platinum, palladium, nickel and mixtures thereof. Themetals may be also added by impregnation. Typical ion exchangetechniques would be to contact the particular zeolite with a salt of thedesired replacing cation or cations. Although a wide variety of saltscan be employed, particular preferance is given to chlorides, nitratesand sulfates.

Representative ion exchange techniques are disclosed in a wide varietyof patents including U.S. Pat. Nos. 3,140,249, 3,140,251 and 3,140,253.

Following contact with the salt solution of the desired replacingcation, the zeolites may be washed with water and dried at a temperatureranging from 150° F to about 600° F and thereafter may be heated in airor other inert gas at temperatures ranging from about 500° F to 1,700° Ffor periods of time ranging from 1 to 48 hours or more.

It is also possible to treat the zeolite with steam at elevatedtemperatures ranging from 800° F to 1,600° F and preferably 1,000° F and1,500° F if such is desired. The treatment may be accomplished inatmospheres consisting partially or entirely of steam. A similartreatment can be accomplished at lower temperatures and elevatedpressure, e.g. 350°-700° F at 10 to about 200 atmospheres.

Reforming in the presence of the catalyst described herein generallytakes place at about 0.5 to about 50 WHSV, about 800° to about 1050° F,at about 85 to about 500 psig pressure and about 1 to about 10 molarratio of hydrogen to hydrocarbons. Such conditions are referred to as"reforming conditions". Preferably the WHSV is about 1 to about 20. Itis understood that one or more reactors in sequence may be employed inthe reforming operation. The catalyst of our invention may containzeolite composite A, whether a physical or an intimate mixture, in allor only part of the reactors. Preferably zeolite composite A comprisesan intimate mixture of the zeolite particles in theplatinum-metal-alumina base, and is used in the last reactor.

As is shown in Example 1, infra, the zeolite containing composite may beachieved by pre-milling a conventional reforming composition alone in aball mill for 24 hours, mixing the premilled composition with thezeolite and ballmilling for two hours. This is generally followed bypelleting the final composite to a desired pellet size. Other methods ofcompositing are also useful. For example, the zeolite may be added toalumina sols or slurries either before or after the Pt metal is added.

In preparing the zeolitic composite the proper balance between theamount of zeolitic component and the conventional reforming catalystcomponent will depend upon the charge stock and operating conditions.However, it should be noted that one of the advantages of this inventionlies in the degree of activity with attendant stability, that thezeolitic component possesses. This high activity, while usefully high upto sizes of 10 microns, will be highest when crystallites are less thanabout 2 microns in size, preferably less than about 1 micron, in weightmean particle diameter, allows for an appreciable degree of flexibilityin catalyst composition within the bounds defined for the K factor, andin operating conditions, including in this regard the presence ofmaterials normally thought of as inhibitors in the reforming process.These inhibitors include nitrogen and sulfur containing compounds.

Generally ion exchange, washing, calcination, steaming and other suchoperations performed on the zeolite should be carried out prior tocombining with the carrier material. Admixture of the zeolite with theconventional reforming catalyst may be accomplished by physically mixingthe same either directly or after compositing in a matrix.

When the zeolite catalyst and conventional reforming catalyst are mixedas large particles, for example, greater than about 40 mesh, the zeolitemay be dispersed in a hydrous oxide matrix such as silica, alumina,magnesia and clay. Generally, the amount of zeolite will fall within therange of from about 1% to about 70% by weight of the zeolite-matrixsystem.

Additionally, the platinum type metal may be added to the zeolite,either before or after admixture thereof with a matrix. When thecomposite comprises an intimate mixture of zeolite and conventionalreforming catalyst, the platinum type metal may be combined with thealumina, either before or after incorporation of the zeolite.

In all these various embodiments, the product aging is diminished andthe selectivity is substantially changed at a given octane number fromthat given by the conventional reforming catalyst alone at the sameoctane severity. In all cases the gaseous products contain more C₃ andC₄ than C₁ and C₂. Further, the operating severity needed to reach agiven octane number is less for the combination catalyst of thisinvention than the reforming catalyst alone.

The naphtha charge stocks which can be reformed over the catalysts ofthis invention include typical reforming stocks, namely virgin naphthas,cracked naphthas and partially reformed naphthas.

The following examples will illustrate the advantages of the catalyst ofthis invention.

EXAMPLE 1

This example illustrates the preparation of one of the zeolites used inthe practice of this invention, i.e. HZSM-5. This component was made asfollows:

    ______________________________________                                        A.   Sodium aluminate solution                                                     0.56 lbs. NaAlO.sub.2  (44.7 wt.% Al.sub.2 O.sub.3                                                   33.5 wt.% Na.sub.2 O                                                          21.8 wt.% water                                        14.0 lbs. H.sub.2 O                                                      B.   Sodium silicate solution                                                      44.7 lbs. Q Brand Silicate                                                                           28.9 wt.% SiO.sub.2                                                           8.9 wt.% Na.sub.2 O                                                           62.2 wt.% water                                        56.0 lbs. water                                                          C.   Quaternary salt solution                                                      5.6 lbs. tetrapropyl--                                                                         ammonium bromide                                             28.0 lbs. water                                                          D.   Acid solution                                                                 4.47 lbs. H.sub.2 SO.sub.4 97 wt.%                                            14.0 lbs. water                                                          ______________________________________                                    

These solutions were mixed together by adding solution C to solution B,then adding solution A to solution BC, followed by adding solution D tosolution ABC. All of these solutions were added together while stirringrapidly. The resulting mixture was heated to 200°-210° F and held for167 hours until the crystalline aluminosilicate product formed.

The synthesized ZSM-5 was then washed free of soluble salts, dried, andcalcined to remove the combustible organics. The calcined crystallineZSM-5 was subsequently contacted four times with a hot solution of 5 wt.% ammonium chloride to reduce the residual sodium content to about 0.01wt. %. Filtration was used to separate the crystallites from theexchange solution after each contact. Finally the exchanged NH₄ ZSM-5was washed free of chloride ion, dried at 230° F, and calcined for 10hours at 1000° F.

The resulting HZSM-5 was composited with a commercial reforming catalystcontaining 0.35 wt. % Pt and 0.35% chloride on an eta-alumina base (RD150 C as manufactured by Engelhard Mineral and Chemical Company).Compositing was achieved by ballmilling for two hours. The conventionalreforming catalyst was pre-milled alone in a ball mill for 24 hoursprior to compositing with the HZSM-5 prepared above. The final compositewas pelleted by slugging to form 1/2" diameter pellets which werecrushed to 14 to 25 mesh. These particles had an apparent density of0.76 g/cc and a Relative Activity value of 46.5.

The reforming activity of this composite, referred to as the catalyst ofExample 1, was tested with a pretreated C₆ -330° F Kuwait naphtha as thecharge stock (see Table 4). The results of this test are summarized inTable 5. The conditions of the run are shown in the table. Thiscatalyst, which contains 10% HZSM-5 (by weight) produced 37.7% C₅ ⁺liquid product at an aromatic level of 80.2 weight percent for the 12liquid hourly space velocity, (LHSV) run. At 50 LHSV the C₅ ⁺ producthas increased to 56.9% and the aromatics level approached 50%, withexcellent gaseous product distribution. Thus, this catalyst with a Kvalue of 46.5 is useful not for conventional reforming but rather isuseful for producing high yields of C₃ 's and C₄ 's along with highoctane gasoline.

EXAMPLE 2

A composite which contained 10% (by weight) of HZSM-5 was prepared usingthe same materials and techniques described in detail under Example 1except that the same HZSM-5 was steamed for 20 hours at 1225° F with100% steam at atmospheric pressure prior to compositing. The finalcomposite in 14 to 25 mesh size had an apparent density of 0.73 g/cc anda Relative Activity value of 31.1.

The reforming activity of this composite was also tested with apretreated C₆ -330° F Kuwait naphtha (Table 4) as the charge stock. Theresults of this test with this composite spread throughout the entirereforming reactor are summarized in Table 5. The conditions of the runare shown in the table. The K factor for this system was 31.1 and is nota catalyst of this invention, since it is still over active like Example1, and like Example 1, it is useful not for conventional reforming butfor producing high yields of C₃ 's and C₄ 's along with high octanegasoline.

In the front 90 volume percent of the catalyst bed of a reformer reactor(nearest the inlet) was placed 3.5 cc of a pure commercialplatinum-rhenium on alumina. In the exit 10 volume % of the reactor wasplaced 0.5 cc of the composite prepared above in Example 2. The totalcatalyst system with a K factor of 4.0 was tested for reforming activitywith a pretreated C₆ -330° F Kuwait Naphtha. The conditions and resultsare shown in Table 5. When this catalyst was tested as in Table 5 theproduct distribution at both 900° and 920° F improved to give moreliquid product than the system above where the 10% steamed HZSM-5 wasused throughout the bed. Likewise the gas distribution was vastlysuperior to the product distributions obtained with the commercialbi-metallic platinum-rhenium-alumina alone at 940° F. These data areshown in Table 5 and indicate that the addition of a small amount ofHZSM-5 composite caused a great change in the product distribution;specifically, in the C₄ and lighter product.

In all of the runs presented in Table 5 with zeolite catalysts, thecombined C₃ and C₄ concentrations in the gas product exceeds 75 weightpercent, so that the C₁ -C₂ concentration never exceeds about 20%. In atypical commercial platinum/rhenium on alumina reforming run in theabsence of a ZSM-5 type zeolite, as shown in Table 5, C₁ -C₂concentrations account for at least about 40% (wt.) of the gas product.

                  TABLE 4                                                         ______________________________________                                        Physical Properties of Hydrodesulfurized                                      Reforming Naphtha Feed.sup.1                                                                            C.sub.6 -290° F                                          C.sub.6 -330° F                                                                      North America                                       Naphtha Source                                                                            Kuwait Naphtha                                                                              Mid-Continent                                       ______________________________________                                        Specific Gravity                                                                          0.7286        0.7385                                              Sulfur, ppm 1.0           0.8                                                 Nitrogen, ppm                                                                             <0.2          <0.2                                                Chlorine, ppm                                                                             <0.1          0.7                                                 Composition, vol. %                                                           C.sub.4 and lighter                                                                       trace         none                                                iC.sub.5    0.1           0.1                                                 nC.sub.5    0.5           0.6                                                 C.sub.6 plus                                                                              99.6          99.3                                                Composition, wt.%                                                             Paraffins   68.0          50.9                                                Monocycloparaffins                                                                        19.5          40.2                                                Dicycloparaffins                                                                          1.1           0.1                                                 Aromatics   11.4          8.6                                                 Research Octane                                                               Number      49            55                                                  ______________________________________                                         .sup.1 Naphthas referred to herein were pretreated with pure hydrogen at      500 psig, 700° F, 5 LHSV over a commercial cobalt molybdena            hydrotreating catalyst.                                                  

                  TABLE 5                                                         ______________________________________                                        C.sub.6 -330° F Kuwait Naphtha.sup.(1) Reforming Over                  HZSM-5/Pt/Al.sub.2 O.sub.3                                                                  Fresh Catalyst                                                                             Steamed Catalyst                                   Catalyst      of Example 1 of Example 2                                       Temp, ° F                                                                            900    900    900  900  900  950                                LHSV (vol.Liq.per                                                                           12     50     50   50   12   12                                   vol. cat. per hr.)                                                          Pressure (psig)                                                                             200    200    200  200  200  200                                Hours on Stream                                                                             4.5    5      24   5    5    10                                 Weight Charge, grams                                                                        2.19   2.19   2.19 2.19 2.19 2.19                               Weight Product, grams                                                                       2.04   2.07   2.12 2.09 2.16 1.91                                 Liquid, grams                                                                             0.81   1.19   1.23 1.90 1.60 1.26                                 Gas, grams  1.23   0.88   0.89 0.19 0.56 0.64                               Wt. % Recovery                                                                              93.4   94.5   97.0 95.8 98.6 87.3                               Wt. % C.sub.5 +                                                                             37.7   55.1   56.9 87.0 73.7 58.9                               Wt. % C.sub.4 -                                                                             55.8   39.4   40.1 8.8  24.9 23.4                               Wt. of Arom. in C.sub.5 +                                                                   80.2   49.9   48.2 33.3 46.0 55.2                               Gas Composition, Wt. %                                                        C.sub.1       1.6    0.8    0.7  1.7  1.4  0.9                                C.sub.2       11.4   6.6    7.0  7.2  4.3  9.2                                C.sub.3       66.7   66.7   67.5 69.8 62.5 72.1                               C.sub.4       19.2   24.1   23.1 20.2 29.8 15.3                               C.sub.5       1.1    1.7    1.6  1.1  1.9  2.6                                Cat. Vol. (cc)                                                                              0.55cc 0.12cc 0.12cc                                                                             0.12cc                                                                             0.5cc                                                                              0.5cc                                            Commercial                                                                    Catalyst.sup.(2)                                                Catalyst      Pt/Re/Al.sub.2 O.sub.3                                                                      Example 2.sup.(3)                                 Temp. ° F                                                                            940      940      920    900                                    LHSV          1.5      1.5      1.5    1.5                                    Pressure, psig                                                                              200      200      200    200                                    Hours on Stream                                                                             22       45       5      24                                     Weight Charge, grams                                                                        --       2.19     2.19   2.19                                   Weight Product, grams                                                                       --       2.01     2.06   2.17                                     Liquid, grams                                                                             --       1.49     1.37   1.48                                     Gas, grams  --       0.52     0.69   0.69                                   Wt. % Recovery                                                                              --       91.8     94.2   96.4                                   Wt. % C.sub.5 +                                                                             --       68.4     63.3   66.5                                   Wt. T C.sub.4 -                                                                             --       23.4     30.9   29.9                                   Wt. % Arom. in C.sub.5 +                                                                    62.8     54.6     62.2   63.6                                   Gas Composition, Wt.%                                                         C.sub.1       15.4     9.8      5.9    0.6                                    C.sub.2       45.4     32.3     14.8   5.1                                    C.sub.3       32.6     40.9     51.7   63.8                                   C.sub.4       6.3      15.9     25.4   27.9                                   C.sub.5       0.3      1.1      2.0    2.5                                    Cat. Vol. (cc)                  4.0cc                                         ______________________________________                                         .sup.(1) The properties of the charge stock used in these runs are listed     in Table 4.                                                                   .sup.(2) The catalyst contained 0.35% by weight of each of platinum and       rhenium. The alumina used was eta alumina having a crystal size of 40-60      Angstroms.                                                                    .sup.(3) Test involving the catalyst system having conventional reforming     catalyst in first 90% of the reactor and the catalyst comprising steamed      HZSM-5 in the last 10% of the reactor.                                   

EXAMPLE 3

In preparing this catalyst composite containing 1% wt. steamed HZSM-5and 99 wt. % commercial Pt-alumina, the individual components wereprepared separately and then composited.

In this case the ZSM-5 was synthesized by first pre-reacting thefollowing solutions:

    ______________________________________                                        A.   Sodium silicate solution                                                                                28.9 wt.% SiO                                       42.2 lbs. Q Brand Silicate                                                                               8.9 wt.% Na.sub.2 O                                                          62.2 wt.% H.sub.2 O                                 58.8 lbs. water                                                                Sp. Gr. 1.151 at 73° F                                           B.   Acid alum solution                                                            72.2 lbs. water                                                               1.44 lbs. Al.sub.2 (SO.sub.4).sub.3 . 18H.sub.2 O                             3.52 lbs. H.sub.2 SO.sub.4                                                    15.8 lbs. NaCl                                                                 Sp. Gr. 1.158 at 85° F                                           ______________________________________                                    

These solutions were mixed together continuously through a mixing nozzleflowing the acid solution at 538 cc/min and the silicate solution at 498cc/min forming an 8.9 pH hydrogel. This mixture was formed into beadhydrogel in the typical bead-forming method. This involves flowing theresulting hydrosol into an oil layer. The stream forms beads that gelinto firm bead hydrogel. The resulting bead hydrogel was charged to a 30gallon autoclave along with 2.8 lbs. tri-n-propyl amine and 2.44 lbs. ofn-propyl bromide. This reaction mixture was allowed to react, whilestirring, for 19 hours at about 275° to 320° F, forming the crystallineorganoaluminosilicate, ZSM-5.

The crystalline product was separated from the supernatent liquor byfiltration, followed by water washing at about 190° F to remove allsoluble salts. The washed material was dried at 230° F and was calcinedfor 3 hours at 700° F in air to remove all carbonaceous material. Theammonium chloride base exchange of this calcined ZSM-5 consisted of 4-1hour stirred contacts at 190°-200° F with ammonium chloride using 5 mlof 5 wt. % ammonium chloride per gram of calcined ZSM-5. The slurry wasfiltered after each contact, followed by water washing free of chlorideion after last contact. The washed cake was subsequently dried at 230° Fand re-calcined for 10 hours at 1000° F, followed by steaming at 1225° Ffor 24 hours with 100% steam at atmospheric pressure.

The resulting steamed HZSM-5 was composited with ballmilled commercial0.35 wt. % Pt on eta-alumina as described under Example 1, the relativequantities being such as to give 1% HZSM-5 in the final composite. Thefinal composite pelleted and sized 14 to 25 mesh had an apparent densityof 0.70 g/cc and had a Relative Activity value of 3.4.

The reforming activity of this catalyst composite was tested throughoutthe bed with the C₆ -330° F Kuwait Naphtha in Table 4 as a charge stock.The K value was 3.4, the same as the Relative Activity value. Theconditions of the run and the results are shown in Table 6. Theseresults indicate that even at extremely low levels of intimately mixedHZSM-5 (Example 3 composite) the combined C₃ -C₄ concentration in thegas product is 80% or greater. Even when the pressure was lowered to 100psig, no apparent effect was observed on product distribution.Additionally, this catalyst showed no indication of aging during thecourse of operation.

                                      TABLE 6                                     __________________________________________________________________________     C.sub.6 -330° F Kuwait Naphtha Reforming With Steamed 1%              HZSM-5-99% (0.35 Pt/nAl.sub.2 O.sub.3).sup.(1)                                __________________________________________________________________________    Catalyst: Example 3; H.sub.2 /HC 7/1; Charge: C.sub.6 -330 Kuwait             Naphtha; LHSV 1.5                                                             Temp. ° F (920° F)                                                          918                                                                              916                                                                              917                                                                              917                                                                              917                                                                              918                                                                              918                                                                              918                                                                              918  916                                  LHSV.sup.(2)                                                                              1.5                                                               Pressure (psig)                                                                           200                     200/100                                                                            100                                  Hours on Stream                                                                           4  12 32 35 55 59 83 103                                                                              108  127                                  Weight Charge, grams                                                                      2.18                                                                             2.19                                                                             2.19                                                                             2.20                                                                             2.20                                                                             2.21                                                                             2.22                                                                             2.22                                                                             2.23 2.22                                 Weight Product, grams                                                                     1.16                                                                             1.80                                                                             1.80                                                                             1.92                                                                             2.01                                                                             1.68                                                                             2.23                                                                             1.98                                                                             2.08 2.10                                   Liquid, grams                                                                           0.71                                                                             1.14                                                                             1.19                                                                             1.26                                                                             1.39                                                                             1.28                                                                             1.41                                                                             1.26                                                                             1.39 1.39                                   Gas, grams                                                                              0.45                                                                             0.66                                                                             0.61                                                                             0.66                                                                             0.61                                                                             0.40                                                                             0.82                                                                             0.72                                                                             0.69 0.71                                 Wt. % Recovery                                                                            53.1                                                                             82.3                                                                             82.2                                                                             87.2                                                                             91.2                                                                             76.1                                                                             100.1                                                                            89.1                                                                             93.4 94.5                                 Wt. % C.sub.5 +                                                                           32.7                                                                             52.6                                                                             54.7                                                                             57.9                                                                             63.7                                                                             57.9                                                                             64.3                                                                             57.2                                                                             63.0 63.3                                 Wt. % C.sub. 4 -                                                                          20.4                                                                             29.7                                                                             27.5                                                                             29.3                                                                             27.4                                                                             18.2                                                                             25.8                                                                             31.8                                                                             30.3 31.2                                 Wt. % Arom. in C.sub.5 +                                                                  74.1                                                                             66.8                                                                             62.8                                                                             63.8                                                                             62.4                                                                             60.2                                                                             61.3                                                                             57.9                                                                             62.1 60.9                                 Gas Composition, wt. %                                                        C.sub.1     5.4                                                                              4.1                                                                              4.1                                                                              2.2                                                                              4.5                                                                              4.3                                                                              3.3                                                                              3.0                                                                              3.3  2.6                                  C.sub.2     20.8                                                                             15.6                                                                             14.1                                                                             10.2                                                                             12.4                                                                             15.2                                                                             11.6                                                                             9.9                                                                              10.2 8.2                                  C.sub.3     58.3                                                                             58.6                                                                             55.5                                                                             54.9                                                                             55.7                                                                             59.8                                                                             52.7                                                                             54.6                                                                             54.4 55.6                                 C.sub.4     14.9                                                                             20.3                                                                             24.8                                                                             30.1                                                                             25.6                                                                             19.7                                                                             29.8                                                                             30.2                                                                             39.8 31.4                                 C.sub.5     0.6                                                                              1.4                                                                              1.6                                                                              2.6                                                                              1.8                                                                              0.8                                                                              2.6                                                                              2.3                                                                              2.3  2.2                                  __________________________________________________________________________     .sup.(1) For properties of charge stock see Table 4.                          .sup.(2) Catalyst: 4.0 cc, 2.85 g                                        

EXAMPLE 4

The composite of Example 3 spread throughout the reactor was tested forits reforming activity with a C₆ -290° F Mid-Continent naphtha (seeTable 4) under conditions shown in Table 7. The K factor for thiscatalyst was 3.4. The results are compared with a standard commercial0.6 wt.% platinum on alumina in Table 7. At the same temperature, 905°F, the catalyst of this invention (as exemplified by Example 4) shows aC₅ + clear research octane gain of 7.3 numbers over the standard 0.6wt.% Pt/Al₂ O₃ (101.8 versus 94.5). The comparison of these twocatalysts at more nearly the same octane level (standard Pt/Al₂ O₃ at905° F, catalyst of Example 3 at 807° F) shows more than a 35° Fadvantage for the HZSM-5 catalyst over the standard.

The gaseous product distributions at the 94.5/96.4 octane level for theliquid product show a decrease in C₁ + C₂ yield with a correspondingincrease in C₃ and C₄ yields. In the C₄ isomer fraction, the isomerdistribution shows isobutane yield is greater than normal butane yieldfor the ZSM-5 composite of Example 3, whereas for the standard Pt/Al₂ O₃this ratio is reversed.

                  TABLE 7                                                         ______________________________________                                        C.sub.6 -290 Mid-Continent Naphtha Reforming.sup.1                                                      Example  Example                                    Catalyst:   0.6 wt.% Pt/Al.sub.2 O.sub.3                                                                4        4                                          ______________________________________                                        Pressure (psia)                                                                           200           200      200                                        Moles H.sub.2 /mole HC                                                                    9.6           9.6      9.6                                        LHSV        1.7           1.7      1.7                                        Temperature ° F                                                                    905           905      870                                        C.sub.5 + RNO+O                                                                           94.5          101.8    96.4                                       C.sub.1 + C.sub.2 (wt.%)                                                                  1.8           3.0      1.6                                        C.sub.3 (wt.%)                                                                            2.4           9.1      7.7                                        iC.sub.4 (wt.%)                                                                           1.3           5.7      5.5                                        nC.sub.4 (wt.%)                                                                           1.6           4.1      3.6                                        C.sub.5 + (vol. %)                                                                        83.4          69.7     74.4                                       C.sub.4 + (vol. %)                                                                        87.1          82.3     85.9                                       ______________________________________                                         .sup.(1) Properties of naphtha charge in Table 4.                        

EXAMPLE 5

18.6 cc of a commercial conventional reforming catalyst containing 0.6wt.% Pt on eta-Al₂ O₃ was placed in the inlet end of a reforming testreactor. This was immediately followed (toward exit end) by 6.4 cc ofthe composite of Example 3. This reactor load with a K factor of 2.5 wasplaced in an isothermal reforming test unit and evaluated for itsactivity toward reforming the C₆ -290° F Mid-Continent naphthacharacterized in Table 4. This activity is compared with the standardPt/Al₂ O₃ under identical test conditions as shown in Table 8 along withthe results. The catalyst of this invention produced a C₅ + liquidproduct having an octane number which is 2.6 research octane numbersgreater than the product from the standard Pt/Al₂ O₃. Furthermore, thiswas accomplished with a loss of only 4% C₅ ⁺ yield and only 1.5% C₄ ⁺yield. The net C₁ + C₂ yield for the catalyst herein claimed was lessthan from the standard (2.1 versus 2.3 wt. percent based on charge).Therefore, if the standard Pt/Al₂ O₃ catalyst was run at increasedseverity (e.g. higher temperature) to give the same octane number levelfor the liquid product, the yield of methane plus ethane would besubstantially greater than for the HZSM-5 catalyst composite. This is avery desirable catalytic property, since it leads to higher hydrogenpurity in operations using recycle gas. The gain in C₃ and C₄ yield atthe expense of C₁ + C₂ is also a very desirable result.

                  TABLE 8                                                         ______________________________________                                        Advantage of Split Bed-HZSM-5 Contained in Pt/Al.sub.2 O.sub.3                in Reforming a C.sub.6 -290° F Mid-Continent Naphtha.sup.(1)           Catalyst       Standard Pt/Al.sub.2 O.sub.3                                                                Example 5                                        ______________________________________                                        Hydrogen/Hydrocarbon                                                          (mol/mol)      4             4                                                Vol. Chg/Vol. Cat/Hr                                                                         1.7           1.7                                              Pressure, psia 200           200                                              Temperature    900           900                                              Product Properties                                                            C.sub.5 + Res. Octane (clear)                                                                95.3          97.9                                             C.sub.5 + vol. Yield                                                                         82.6          78.6                                             C.sub.4 + vol. Yield                                                                         87.2          85.7                                             C.sub.1 + C.sub.2 wt.% of Charge                                                             2.3           2.1                                              C.sub.3        3.1           5.1                                              iC.sub.4       1.7           3.1                                              nC.sub.4       1.9           2.5                                              ______________________________________                                         .sup.(1) Naphtha properties are shown in Table 4.                        

Examples 6-17 illustrate specifically the role the K factor plays in thepresent invention.

EXAMPLE 6

A commercially available conventional reforming catalyst containing 0.37wt.% platinum, 0.20 wt.% rhenium and 0.9% chloride impregnated on agamma alumina support was tested for catalytic stability by thefollowing method. Twenty milliliters of the catalyst was loaded into adownflow isothermal reforming reactor. The reactor was heated to 960° Funder a flow of pure hydrogen (40 liters/hour) at 150 psig. Thetemperature was lowered to 850° F, pure hydrogen addition stopped and agaseous mixture of hydrogen sulfide in hydrogen (40 ppm H₂ S inhydrogen) was passed over the catalyst until hydrogen sulfide wasdetected in the exit gas. The H₂ S/H₂ mixture was discontinued and purehydrogen started at a flow rate of 40.2 liters/hr. Liquid charge stockwas pumped into the reactor at a rate of 36 milliliters per hour. Thecharge stock used here was a hydrogen pretreated C₆ -330° F. Arabianlight naphtha with the properties shown in Table 9. Temperature wasincreased to 900° F and held for 1 hour. Final temperature adjustmentwas made.

Temperature was chosen here and in subsequent examples to give at thestart of the run a C₅ ⁺ liquid product having a clear research octanenumber of 100 ± 1.5 octane, which for this catalyst was 960° F.

In this aging stability evaluation the average decline in octane numberof C₅ ⁺ liquid product per day over the course of the run was 0.75octane number per day. This is the averaged drop over a 16 day run inwhich the octane number declined from 99.7 on the first day to 88.7 onthe 16th day. Periodic octane numbers were taken during the runs. C₅ ⁺volume liquid yield for this catalyst at the start of the run was 73%.C₃ ⁺ volume yield was 90%.

Since this is the standard catalyst against which our experimentalcatalysts were rated for K, by definition K was 1.0.

                  TABLE 9                                                         ______________________________________                                        Charge Stock: C.sub.6 -330° F. Arabian Light Naphtha                   Wt. %                  Properties                                             ______________________________________                                        Paraffins              68.8                                                   Naphthenes             18.4                                                   Aromatics              12.7                                                   Specific Gravity       API 63.0                                               ASTM Distillation, ° F                                                 IBP                    168                                                    10%                    199                                                    30%                    218                                                    50%                    241                                                    70%                    268                                                    90%                    296                                                    EP                     322                                                    Clear Research Octane  37.8                                                   Avg. Mol Wt.           106.4                                                  Wt.% Combined Hydrogen 14.8                                                   ______________________________________                                    

Run Conditions were:

150 psig total inlet pressure

7 moles of hydrogen feed per mole of hydrocarbon feed

1.8 volumes of charge stock per volume of catalyst per hour

EXAMPLE 7

A composite catalyst which contained 1% HZSM-5 was prepared as follows:The HZSM-5 was synthesized by the following procedure:

In this case the ZSM-5 was synthesized by first preheating the followingsolutions:

    ______________________________________                                        A.  Sodium silicate solution                                                                                  (28.9 wt.% SiO.sub.2                              94.5 lbs. of Q-Brand Silicate                                                                              8.9 wt.% Na.sub.2 O                                                          62.2 wt.% H.sub.2 O                               54.9 lbs. H.sub.2 O                                                       B.  Acid Aluminum Sulfate solution                                                3.02 lbs. Al.sub.2 (SO.sub.4).sub.3 . H.sub.2 O                                (17.2% Al.sub.2 O.sub.3                                                      7.88 lbs. H.sub.2 SO.sub.4 (97%)                                              17.7 lbs. NaCl                                                                56 lbs. H.sub.2 O                                                         ______________________________________                                    

These solutions were premixed in a nozzle and then added to the stirredautoclave. To this mixture in the autoclave was added;

10 lbs. methyl ethyl ketone

6.36 lbs. tripropyl amine

5.47 lbs. n-propyl bromide

and reacted in the static state, no mixing. During this organic reactionthe autoclave was heated to 240° F and held for 14-15 hours to allow theorganics and the gel to prereact.

The mixture was then agitated vigorously and heated to and held at 320°F for 4 1/2 hours. The volatile organics were then distilled off themixture at this point.

The crystallites were then filtered, washed and exchanged in a mannersimilar to example 3. However, in this case the calcined crystals ofHZSM-5 were steamed at 1100° F rather than at 1225° F as in example 3.

This steamed HZSM-5 (1.298 grams) was mixed with 243.5 grams of hydratedcommercial alumina-monohydrate (50.75% solids, obtained from ContinentalOil Co.) in a muller mixer with 25 ml of water for 30 minutes. Thismixture was extruded as 1/32" diameter particles, dried 4 hours at 230°F and heated to 1000° F at a rate of 2° F/minute and held for 10 hours.

A portion of the above extrudate (88.7 g, 99.7% solids) was placed in anevacuation chamber for 30 minutes and impregnated with 70.6 ml of anaqueous solution which contained 0.338 grams of platinum ashexachloroplatinic acid, 0.338 grams of rhenium as perrhenic acid and0.456 grams of chloride as hydrochloric acid. After impregnation theextrudate stood for 1 hour at atmospheric pressure and was then dried at230° F for 3 1/2 hours. The dried extrudate was calcined for 3 hours at1000° F.

The final catalyst composite contained 0.44 wt. % platinum and 0.83%chlorine and had a surface area of 202 square meters per gram.

The Relative Activity factor for the composite of this example asdefined by the o-xylene isomerization test was 6.4.

EXAMPLE 8

The composite catalyst of Example 7 was evaluated for aging stability bythe method discussed in Example 6 except that the catalyst bed differed.The top of the catalyst bed contained 8 cubic centimeters of thecommercial Pt-Re/gamma alumina of Example 6 and bottom 12 cc of the bedwas the composite of Example 7. The K factor for this total catalystsystem was 4.2. All other conditions of the test were the same exceptthat the temperature needed to reach the desired O.N. was 940° F. Thisshows the great increase in activity of this catalyst. The averageoctane number decline during the course of this run was 0.43 octanenumbers per day.

This catalyst system is obviously more stable than the conventionalPt-Re/γ -Al₂ O₃ of Example 6 since the activity declined at a slowerrate. The decline in aging rate in this example was 43% less than theaging rate of the standard catalyst of Example 6. Further, the activityof the catalyst of this example is greater since a lower temperature wasnecessary to give a C₅ + liquid product having a 100 clear researchoctane number. The C₅ + liquid yield at the start of the run was 69volume %. The C₃ + yield was 95 volume %.

EXAMPLE 9

A composite catalyst was prepared which contained one wt. % steamedHZSM-5 and 99 wt. % of the conventional reforming catalyst from Example6. The steamed HZSM-5 was prepared by the method indicated in Example 7.The Pt-Re on alumina material of Example 6 was ball-milled 24 hoursprior to using. The composite catalyst of this example was an intimatemixture of 0.90 grams of the HZSM-5 prepared in Example 7 and 90.0 gramsof the Pt-Re/γ-Al₂ O₃ of Example 6. The composite was mixed for 2minutes in an electric mixer and then ballmilled for 1 hour. The powdermixture was pelleted and sized to 14/25 mesh particles.

This composite catalyst had a relative activity of 5.2 and was evaluatedby the method described in Example 6. The catalyst bed consisted of 8.0cc of the conventional reforming catalyst of Example 6 in the top of thereactor and 12.0 cc of the composite of this example in the bottom ofthe bed. The K factor of this total catalyst system was 3.5. Thetemperature of this test as 930° F. Thus, this catalyst also is muchmore active than the standard catalyst of Example 6. The C₅ + liquidyield at the start of the run was 70 volume %. The C₃ + yield was 100volume %. The octane decline rate of the dual catalyst system describedhere was 0.31 octanes per day. Its stability is far better than that ofthe conventional reforming catalyst described in Example 6 whichdeclined at the higher rate of 0.75 octanes/day. The decline in agingrate compared to the standard conventional reforming catalyst (Example6) is 59%.

EXAMPLE 10

The composite of Example 3 was evaluated by the method described inExample 6. The catalyst bed contained 8.0 cc of the composite of Example6 in the top of the bed and 12.0 cc of the catalyst of Example 3 in thebottom of the bed. This system had a K factor of 2.4. The temperature ofthis test was 930° F, again showing the increased catalyst activity. Theaverage octane decline for this test was 0.37 octanes per day which ismuch less than the decline for the conventional reforming catalyst ofExample 6. The decline in aging rate was 51% of the decline rate for thestandard reforming catalyst of Example 6. The C₅ ⁺ yield was 73 volume%. The C₃ ⁺ yield was 96 volume %.

EXAMPLE 11

The composite of this example was prepared by mixing 10 wt. % steamed H+(TEA) mordenite with 90 wt. % of the Pt-Re/γ - Al₂ O₃ of Example 6.

The tetraethylammonium mordenite (referred to as TEA mordenite) wasprepared as follows:

    ______________________________________                                        A.     Sodium aluminate solution                                                     51 g. NaAlO.sub.2                                                                43.1 wt. % Al.sub.2 O.sub.3, 33.1 wt. % Na.sub.2 O,                           24.3 wt % H.sub.2 O                                                        53.6 g. NaOH                                                                  123 g. Water                                                           B.     Organic salt solution                                                         246 g. tetraethylammonium chloride monohydrate                                123 g. water                                                           C.     Silicate solution                                                             1300 g. colloidal silica sol(30% SiO.sub.2)                            ______________________________________                                    

1300 g. colloidal silica sol (30% SiO₂) These solutions were mixedtogether by adding solution A to B, mixing thoroughly, then addingsolution C followed by 10 minutes mixing. The mixture was then chargedto a 2 liter Parr autoclave and held at 175° C for 8 days underpressures of 400-830 psig without stirring. The resulting product wasseparated from the liquid by filtering and washing.

The crystalline product identified as TEA mordenite by x-ray analysiswas first calcined for 10 hours at 1000° F and then exchanged with NH₄Cl to remove residual sodium. In this exchange process 67.5 grams of theNa (TEA) mordenite were contacted with 675 ml of 10% NH₄ Cl solution forone hour at approximately 180° F. After repeating the NH₄ Cl exchangefour times the (TEA) mordenite was washed until essentially free ofchloride ions. The cake was dried at 230° F, pelleted and sized 30 to 60mesh and recalcined 10 hours at 1000° F. The resulting powder wassteamed for 20 hours at 1100° F in a 100% steam atmosphere prior tocompositing with the conventional reforming catalyst of Example 6 in theratio to constitute 10 wt. % HTEA and 90% Example 6.

This composite catalyst had a relative activity of 4.1 and was evaluatedby the method described in Example 6. The catalyst bed contained 8.0 ccof the conventional reforming catalyst of Example 6 in the top of thebed and 12.0 cc of the composite prepared above in this example in thebottom of the bed. The K factor of this catalyst system was 2.9. Thetemperature of this test was 960° F. The C₅ ⁺ liquid yield at the startof the run was 65 volume %. The C₃ ⁺ yield was 94 volume %. The averageoctane decline for this test was 0.53 octanes per day which is less thanthe decline for the conventional Pt-Re of Example 6. The decline inaging rate compared to the standard reforming catalyst of Example 6 was29%.

EXAMPLE 12

The composite of this example was prepared by mixing one wt. % of apreviously steamed CaY impregnated with platinum ammine solution with 99wt. % of the conventional Pt-Re of Example 6. The particular CaY used inthis composite was prepared by exchanging commercial NaY with CaCl₂solution. The NaY base as exchanged by slurring with 10% CaCl₂ solutionusing 10 cc per gram at 180°-200° F. Six two hour contacts reducedresidual sodium to 1.3 wt. %. The base was then water washed untilchloride free and dried at 230° F. After calcining for 10 hours at 1000°F the zeolite was steamed for 20 hours at 1200° F with an atmosphere of100% steam. The zeolite was platinum as platinum impregnated with onewt. % platinum ammine complex.

The final composite contained 0.314 g of the Pt-CaY prepared above and31.1 g of powdered Pt-Re on alumina of Example 6. The Example 6composite was powdered by ball-milling 24 hours. These powders weremixed on a CRC mill for 2 minutes and pelleted and sized to 14 by 25mesh particles.

This composite catalyst had a relative activity of 2.4 and was evaluatedby the method described in Example 6. The catalyst bed contained 8.0 ccof the composite of Example 6 in the top of the bed and 12.0 cc of thecomposite of this example in the bottom. The K factor for the totalcatalyst system was 1.8. The test temperature for this specific run was940° F, again showing increased catalyst activity. The C₅ ⁺ liquid yieldat the start of the run was 70 volume %. The C₃ ⁺ yield was 94 volume %.The average octane decline for this test was 0.60 octanes per day whichis 20% less than the decline of the conventional Pt-Re of Example 6.

EXAMPLE 13

The composite catalyst of this example was prepared by intimatecombination of one wt. % of zeolite HZSM-35 and 99 wt. % of thecommercial Pt-Re reforming catalyst of Example 6.

The zeolite identified as ZSM-35 was prepared by interacting thefollowing solutions:

    ______________________________________                                        A.        Caustic Silicate Solution                                                     1. 508 g. Q-Brand Sodium Silicate which                                       is 8.9 wt.% Na.sub.2 O, 28.9 wt.% SiO.sub.2 and                                 62.2 wt. % water.                                                           2. 32.5 g. of 50 wt. % NaOH                                                   3. 299 g. water                                                     B.        Acid Alum Solution                                                            1. 88 g. Al.sub.2 (SO.sub.4).sub.3 . 18 H.sub.2 O                             2. 22.5 g. H.sub.2 SO.sub.4                                                   3. 870 g. water                                                     C.        Organic                                                                       1. 150 g. ethylenediamine                                           ______________________________________                                    

The solutions were mixed in the following order: solution C mixed with Aand then with B for 15 minutes. This mixture was charged to a stirred 2liter Parr Autoclave and heated to 180° C. The stirred mixture was heldat 175°-180° C for 5 days under a pressure of 150-170 psig. Theresulting crystalline zeolite identified as ZSM-35 was separated fromthe supernatant liquid by filtration and washing.

Properties of the resulting ZSM-35 product were as follows:

    ______________________________________                                        X-ray - The pattern corresponded to that shown                                   in Table 10                                                                ______________________________________                                        Sorptions:                                                                    normal hexane         6.4 wt.%                                                cyclohexane           0.9 wt.%                                                H.sub.2 O            10.6 wt.%                                                Composition                                                                   SiO.sub.2            81.3  wt.%                                               Al.sub.2 O.sub.3      9.38 wt.%                                               ______________________________________                                    

Zsm-35 was calcined 10 hours at 1000° F in air and then base exchangedat 180° F with 286 ml of 10 wt.% NH₄ Cl solution per 28.6 g of ZSM-35with stirring. Four contacts left the zeolite essentially sodium free.Finally the exchanged ZSM-35 was washed free of residual chloride ionand then recalcined for 10 hours at 1000° F.

                  TABLE 10                                                        ______________________________________                                        d(A)                I/Io                                                      ______________________________________                                        9.5  ± 0.30      Very Strong                                               7.0  ± 0.20      Medium                                                    6.6  ± 0.10      Medium                                                    5.8  ± 0.10      Weak                                                      4.95 ± 0.10      Weak                                                      3.98 ± 0.07      Strong                                                    3.80 ± 0.07      Strong                                                    3.53 ± 0.06      Very Strong                                               3.47 ± 0.05      Very Strong                                               3.13 ± 0.05      Weak                                                      2.92 ± 0.05      Weak                                                      ______________________________________                                    

A composite of 0.344 g. of the HZSM-35 and 30.7 g of the conventionalreforming catalyst of Example 6, which was previously powdered byball-milling 24 hours, was mixed 2 minutes in a CRC mill, then pelletedand sized 14 × 25 mesh. This final composite had a relative activity of2.0 and was evaluated by the method described in Example 6 with theexception that at the run temperature of 930° F the octane at thebeginning of the test was only 97.2. The catalyst bed contained 8.0 ccof the Pt-Re on alumina of Example 6 in the top of the bed and 12.0 ccof the composite of this example in the bottom of the bed. The K factorfor this system was 1.6. The average octane decline for this test was0.70 octanes per day. This represents a 6% decrease in aging ratecompared to the standard reforming catalyst of Example 6. The C₅ ⁺liquid yield at the start of the run was 75 volume %. The C₃ ⁺ yield was93 volume %.

The following examples (14-17) are included merely for the purpose ofcomparison.

EXAMPLE 14

The composite catalyst of this example was prepared by intimatecombination of 3 wt. % of steamed zeolite HZSM-35 and 97 wt. % of thePt-Re on alumina catalyst of Example 6. The HZSM-35, prepared by themethod described in Example 13, was steamed for 20 hours at 1100° F in100% steam atmosphere before compositing with the powdered conventionalreforming catalyst of Example 6. This powder mixture was mixed in a CRCmill for 2 minutes and then pelleted and sized 14 to 25 mesh.

The composite had a relative activity of 0.6 and was evaluated by themethod described in Ex. 6. The catalyst bed contained 8.0 cc of thePt-Re/alumina of Ex. 6 in the top of the bed and 12.0 cc of thecomposite of this example in the bottom of the bed. The K factor forthis system was 0.8. The temperature of this test was 950° F. The C₅ ⁺liquid yield at the start of the runs was 74 volume %. The C₃ ⁺ yieldwas 90 volume %. The average octane decline for this test was 0.77octanes per day. Therefore the catalyst system of this example shows noadded stability over the commercial Pt-Re catalyst of Example 6.

EXAMPLE 15

The composite of this example was prepared by mixing 0.25 wt. % of anacid (TEA) mordenite with 99.75 wt. % of powdered Pt-Re ctalyst ofExample 6. The acid TEA mordenite was prepared by the method in Example11 except the calcined zeolite was not subjected to steaming. Thecomposite was pelleted and sized to 14 to 25 mesh particles.

This composite had a relative activity of 1.3 and was evaluated by themethod described in Example 6. The catalyst bed contained 8.0 cc of theconventional reforming catalyst of Example 6 in the top of the bed and12.0 cc of the composite of this example in the bottom of the bed. The Kfactor for this system was 1.2. The temperature of the test was 930° F.The C₅ ⁺ liquid yield at the start of the run was 72 volume %. The C₃ ⁺yield was 95 volume %. The average octane decline for this test was 0.74octanes per day. The small amount of zeolite in this catalyst failed tostabilize this catalyst system.

EXAMPLE 16

The composite catalyst of this example was prepared by compositing onewt. % of a steamed CaY and 99 wt. % of powdered Pt-Re ctalyst of Example6. The CaY was prepared by the method described in Example 12 except theconditions for steaming the freshly calcined CaY was 20 hours at 1300° Fin an atmosphere of 100% steam. This sample which contained no platinum,was mixed thoroughly with Pt-Re/alumina of Example 6 in a CRC mill for 2minutes. The powder mixture was pelleted and sized to 14 × 25 meshparticles.

This composite had a relative activity of 1.1 and was evaluated by themethod described in Example 6. The catalyst bed contained 8.0 cc ofPt-Re catalyst of Example 6 in the top of the bed and 12.0 cc of thecomposite of this example in the bottom of the bed. The K factor of thissystem was 1.1. The test temperature was 950° F. The C₅ ⁺ liquid yieldat the start of the run was 74 volume %. The C₃ ⁺ yield was 90 volume %.The average octane decline for this test was 0.98 octanes per day. Thiscatalyst system is less stable than the catalyst of Example 6.

EXAMPLE 17

The composite of this example was prepared by compositing 1.15 g (2%) ofacid mordenite with 49.15 g. (98%) of the commercial Pt-Re/alumina ofExample 6. The mordenite with a silica to alumina ratio of 10 was acommercial sample designated Zeolon H Type 100. The conventionalPt-Re/alumina of Example 6 had been previously ball-milled for 24 hours.The above composite was ball-milled for 2 hours and then pelleted andsized 14 × 25 mesh. This composite catalyst had a relative activity of0.8 and was evaluated by the method described in Example 6. The catalystbed contained 8.0 cc of the Pt-Re standard of Example 6 in the top ofthe bed and 12.0 cc of the composite of this example in the bottom ofthe bed. The K factor of this catalyst system was 0.9. The temperatureof the test was 960° F. The C₅ ⁺ liquid yield at the start of thr runwas 73 volume %. The C₃ ⁺ yield was 91 volume %. The average octanedecline for this test was 0.88 octanes per day which is more than the0.75 O/D for the commercial Pt-Re catalyst of Example 6.

EXAMPLE 18

Since a substantial gain in stability (decline in aging rate) was foundfor our preferred catalysts in this accelerated test using a simpleisothermal reactor, the following was done to see how large animprovement in aging rate would result in the type of operation usedcommercially, namely, adiabatic, multi-reactor operation.

The HZSM-5 composite of Example 7 (47.5g) was placed in the fourthreactor of an experimental adiabatic reforming unit having four reactorsconnected in sequence. The K factor of this system was 3.0. The standardplatinum-rheniumgamma alumina of Example 6 as described hereinabove, wasplaced in the first, second and third reactors (Case 1).

                  TABLE 10                                                        ______________________________________                                                           Relative  Case 1  Case 2                                   Reactor                                                                              Composite   Activity  Vol. (cc)                                                                             Vol. (cc)                                ______________________________________                                        1      Pt/Re - Al.sub.2 O.sub.3                                                                  1.0       19.7    19.7                                            Catalyst of                                                                   Example 6                                                              2      Pt/Re - Al.sub.2 O.sub.3                                                                  1.0       24.6    24.6                                     3      Pt/Re - Al.sub.2 O.sub.3                                                                  1.0       34.5    34.5                                     4      HZSM-5/Pt/Re                                                                              6.4       47.5    --                                       Al.sub.2 O.sub.3                                                              4      Pt/Re - Al.sub.2 O.sub.3                                                                  1.0       --      47.5                                     ______________________________________                                    

A comparable run was made with all four reactors loaded with thecommercial Pt/Re γ -Al₂ O₃ of Example 6 (Case 2).

The start-up for both cases was identical. The catalyst was heated fortwo hours at 900° F and 200 psig with a fresh hydrogen addition rate of1-2 cubic feet per hour at a recycle rate of 10.24 cubic feet per hour.The temperature was dropped to 700° F, fresh hydrogen additiondiscontinued and 2.5 cu ft/hr of hydrogen containing 400 ppm of hydrogensulfide was fed to the unit with a recycle rate of 8.3 cu fet/hour. Whenadditional H₂ S was no longer consumed by the catalyst, H₂ S additionwas stopped and fresh hydrogen added until a recycle flow rate of 10.24cu ft/hr was established.

A liquid charge stock having the properties shown in Table 11 was pumpedinto the unit at 185 ml/hr. The temperature was increased to 800° F.During a 4 hour period chlorine (0.18 wt % of catalyst) as tertiarybutyl chloride was pumped into the unit in the charge stock. During theremainder of the run chloride was continuously added at the rate of0.046 g (as tertiary butyl chloride) per 100 g. of catalyst per day.

                  TABLE 11                                                        ______________________________________                                        Charge stock: C.sub.6 -370° F Paraffinic Naphtha                       Properties                                                                    ______________________________________                                        PONA, wt.%                                                                    P                     59.0                                                    N                     28.1                                                    A                     12.9                                                    Specific                                                                      Gravity               0.7411                                                  ASTM, ° F                                                              10%                   204                                                     30%                   231                                                     50%                   257                                                     70%                   289                                                     90%                   328                                                     E.P.                  365                                                     ______________________________________                                         The temperature was held at 800° F until the water concentration in     the overhead from the high pressure separator dropped below 130 ppm. The     temperature was increased to 875° F and held until the water     concentration dropped below 110 ppm. The temperature was further increased     to 900° F and was held there for 2 hours. The temperature was then     increased to 930° F. The pressure was 200 psig, the space velocity     was 1.43 vol. of liquid per vol. of catalyst per hour and the total     recycle ratio was 10.4 moles of recycle gas per mole of charge naphtha.

During the run in Case 2, where the inlet temperatures to all fourreactors were kept equal, the temperatures were appropriately increasedup to an end point of 990° F in order to maintain a 100 clear researchoctane number for the C₅ + liquid product. The calculated C₅ + clearresearch octane number of the material leaving the 3rd and entering the4th reactors was 98. A temperature increase at the rate of 2.9° F perday was required to maintain this octane number.

In Case 1, the inlet temperatures to reactors 1, 2 and 3 were keptequal. The temperatures were appropriately increased to maintain a 95clear research octane number for the C₅ + product leaving the 3rdreactor and entering the 4th reactor. This required an increase of 0.4°F per day. The inlet temperature of the 4th reactor at 930° F maintaineda 100 clear research octane number for the C₅ + liquid product from thetotal unit.

The total cycle time for Case 1 far exceeds the cycle time for Case 2.Case 2 reached the end point temperature in 17 days which was 49° Fabove its start-of-cycle temperature. Case 1 in 35 days showed a 15° Fincrease for the first, second and third reactors. Reactor 4 remainedconstant. It is obvious that Case 1 will show far superior cycle lifethan Case 2. This longer cycle life is the result of the superioractivity and stability of HZSM-5 composite in the 4th reactor of Case 1.

What is claimed is:
 1. A reforming catalyst system in which the totalcatalyst comprises (1) from about 1 to about 100% of a compositecomprising(a) an effective amount, up to about 25% by wt. of acrystalline aluminosilicate zeolite of controlled acidity, thealuminosilicate being selected from the group consisting of ZSM-5,ZSM-35 and TEA-mordenite, (b) not less than about 75%, by weight, of acarrier material, (c) from about 0.01% to about 2%, by weight, of aplatinum group metal either alone or in combination with other metals,and (d) from about 0.01 to about 3%, by weight, of a halideand (2) from0% to about 99% of a conventional reforming catalyst compositioncomprising (e) a carrier material, (f) from about 0.01% to about 2%, byweight, of a platinum group metal either alone or in combination withother metals, and (g) from about 0.01% to about 3%, by weight, of ahalidesaid total catalyst system having a K factor from about 1.5 toabout 15, this factor being as defined in the specification in equations2 and
 3. 2. The catalyst of claim 1 in which the metal is platinum. 3.The catalyst of claim 2 in which platinum is associated directly withthe zeolite.
 4. The catalyst of claim 1 in which the metal associatedwith the composite is a combination of platinum and rhenium.
 5. Thecatalyst of claim 4 in which platinum and rhenium are associateddirectly with the zeolite.
 6. A catalyst according to claim 1 whereinthe reforming catalyst comprises platinum on alumina.
 7. The catalyst ofclaim 1 wherein the reforming catalyst comprises platinum and rhenium onalumina.
 8. A catalyst according to claim 1 wherein the zeolite is ZSM-5and has the x-ray diffraction pattern as set forth in Table I.
 9. Acatalyst according to claim 1 wherein the zeolite has been exchangedwith ammonium cations.
 10. The catalyst of claim 1 wherein said zeoliteis present to the extent of up to about 15%.
 11. The catalyst of claim 1wherein the K factor is from about 1.5 to about
 10. 12. The catalyst ofclaim 1 wherein the K factor is from about 2 to about
 5. 13. Thecatalyst of claim 1 wherein the zeolite is mordenite synthesized tocontain quaternary ammonium ions.
 14. The catalyst of claim 13 whereinthe quaternary ammonium ion is tetraethylammonium.
 15. The catalyst ofclaim 1 wherein the zeolite is ZSM-35.
 16. The catalyst of claim 1wherein the activity is controlled by steaming of the zeolite.
 17. Thecatalyst of claim 1 wherein the zeolite has a particle size of not morethan 10 microns.
 18. The catalyst of claim 1 in which the carrier isalumina.